Given:
limx→0 (cos2x − 1) / (cos x − 1)
Step 1: Factor the numerator
cos2x − 1 = (cos x − 1)(cos x + 1)
Step 2: Simplify the expression
= limx→0 (cos x − 1)(cos x + 1) / (cos x − 1)
Cancel (cos x − 1):
= limx→0 (cos x + 1)
Step 3: Apply the limit
As x → 0,
cos x → 1
Therefore,
limx→0 (cos x + 1) = 2
Final Answer:
limx→0 (cos2x − 1)/(cos x − 1) = 2